Construction of the diesel refinery, on a 318-acre site located west of Dickinson in Stark County, N.D. is expected to take approximately 20 months. The refinery will process 20,000 barrels per day of Bakken crude oil. It will employ 400 to 500 employees during peak construction and about 100 employees when it is operating.

North Dakota Governor Jack Dalrymple drove a bulldozer to lead the groundbreaking ceremony. Others participating in the event included the state's congressional delegation, Sen. John Hoeven, Sen. Heidi Heitkamp and Rep. Kevin Cramer, along with state, local and industry officials.

"Bringing this project from concept to construction took the effort of a great many people," said David L. Goodin, president and chief executive officer of MDU Resources. "We especially appreciate the support of Governor Dalrymple, other state officials and state agencies. Their permitting process was rigorous, but at the same time they helped us identify and solve problems that are involved in a complex project such as this."

"This facility will help supply North Dakota's growing diesel fuel market, and will be a good contributor to the state and local economy," said Jennifer G. Straumins, president and chief operating officer of Calumet's general partner. "We look forward to working in a state where officials have demonstrated strong support for economic development."

The facility's engineering and plant design are in the final stages. Westcon has been selected as the general contractor and Ventech Engineering will be the primary equipment and technology provider. MDU Resources' construction businesses, Knife River Corporation and MDU Construction Services Group, are among potential subcontractors. Other MDU Resources' companies involved in the project include Fidelity Exploration and Production Company, which will supply some of the facility's crude oil; WBI Energy, which will supply natural gas service to operate the facility; and Montana-Dakota Utilities, which will supply the facility's electricity needs.

MDU Resources Group, Inc., a member of the S&P MidCap 400 index, provides value-added natural resource products and related services that are essential to energy and transportation infrastructure, including regulated utilities and pipelines, exploration and production, and construction materials and services companies. For more information about MDU Resources, see the company's website atwww.mdu.comor contact the Investor Relations Department atinvestor@mduresources.com.

Calumet Specialty Products Partners, L.P. is a master limited partnership and is a leading independent producer of high-quality, specialty hydrocarbon products in North America. Calumet Specialty Products Partners, L.P. processes crude oil and other feedstocks into customized lubricating oils, solvents and waxes used in consumer, industrial and automotive products. Calumet also produces fuel products including gasoline, diesel and jet fuel. Calumet Specialty Products Partners, L.P. is based in Indianapolis, Indiana and has eleven facilities located in northwest Louisiana, northwest Wisconsin, western Pennsylvania, Texas and eastern Missouri.

Forward-Looking Statements

Except for the historical information contained herein, the matters discussed in this release are forward-looking statements that involve certain risks and uncertainties that could cause actual results to differ materially from results anticipated in the forward-looking statements. These risks and uncertainties include, among other things, the ability of the parties to complete financing of the project, the ability of the parties to obtain required regulatory permits, the cost and time to complete the project, and the availability of crude petroleum product and markets for processed products. These and any other statements about future expectations, beliefs, goals, plans or prospects constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Any statements that are not statements of historical fact (including statements containing the words "believes," "plans," "anticipates," "expects," "estimates" and similar expressions) should also be considered to be forward-looking statements.